They did the job for me. I installed them in two air conditioners. One of them was very problematic and was making a creaking noise, as well as shaking the wall. That stopped. The air conditioner became quiet. The material is indeed a bit hard, but with the weight of the air conditioner, it seems to be as hard as it needs to be. I definitely didn't tighten the screws too tightly to avoid making the material even harder and to allow for some vibration. I tightened the screws just enough to hold the air conditioner in place. That means a little bit of tightening. Then I noticed that the air conditioner grilles were also creaking. I put some papers in the gaps and that stopped the vibrations as well. The only better solution I can think of for anti-vibration would be to have the air conditioner placed on the floor on a thick rubber mat that absorbs every vibration. However, the next best thing is these bases. I have purchased a third set for another air conditioner. I highly recommend them, especially for air conditioners with significant vibration issues. That's where you will see the big difference.

Very good shock absorbers help a lot in the smooth operation of the air conditioner and greatly reduce the noise. Of course, you won't notice this much in the new inverter air conditioners, which work smoothly unless it is next to a cement board, which is exactly next to the bedroom. The big difference will be noticed in the older air conditioners that caused a lot of vibration during startup, shutdown, and operation. However, it still helps a lot even for the new air conditioners. I believe they are comfortable up to 12, I don't know if they will handle the weight, these specific ones may need something more sturdy, just like the more sturdy ones won't work for the 12 because if they are too hard, they won't absorb any vibration. The ones I received are moderate, not too soft or too hard. It requires attention in the selection, if they are too soft, over time they tear and get destroyed, and the air conditioner may come off the base because the two screws that hold it on the edges and are separate screws do not connect, and if the hose is cut, the air conditioner will come off its position. No matter how hard they are, they don't offer anything, they transfer all the vibrations to the base

Generally, the anti-vibration bases, or otherwise known as cinéblock air conditioner bases, do a good job in limiting the resonance noise produced by the external unit of the air conditioner (not the compressor).

Attention, before installing them, you should make sure that the external unit is leveled and properly "tied" because otherwise it will create additional noise from resonance and the cinéblocks will not work properly.

Regarding the product now, these bases have pros and cons.

The pros are that:
- They work like all other cinéblocks, meaning they actually reduce the noise from the external unit, and additionally, these specific bases have integrated bolts, wheels, and dowels, so you simply place them and that's it.

The cons are that:
- Their rubber is quite hard and inflexible, it should be more elastic and "chewy" so that it would work much better and absorb more vibrations.
Also, these specific bases have a large height and inevitably raise the external unit quite high, with all the implications that come with it (definitely 5 to 7 inches).

Personally, I had a problem with the height since it raised the unit too much and then it didn't fit where it was originally placed.

So yes, they work and are very easy to install, but you should confirm if there is enough space and if the external unit can be raised a few inches.